The present invention relates to the configuration of a magnetic recording medium such as a magnetic disk used in the hard disk drives of computers. More particularly, the present invention is directed to the optimum parameters for texturing trenches formed on the nonmagnetic base plate and the processing of the texturing trenches.
Referring to FIG. 5, a conventional metal thin film magnetic recording medium shown generally at 10 includes a nonmagnetic Cr underlayer 2 laminated on a nonmagnetic base plate 1. A Co alloy magnetic layer 3 is laminated in a film form on the nonmagnetic Cr underlayer 2. Thereafter, a diamond like carbon protecting layer 4 is laminated on the Co alloy magnetic layer 3. The carbon protecting layer 4 contains polymer like ingredients.
Also included is a lubricating layer 5, composed of a liquid lubricant, which is disposed on the carbon protecting layer 4. The nonmagnetic base plate 1 can be composed of numerous components including one of an Al alloy, glass, carbon, titanium, or similar components. In recent years, however, Al alloy has found widespread use as the main constituent of conventional nonmagnetic base plates.
The nonmagnetic base plate 1 is covered with a Ni-P (nickel-phosphorus) plating layer 1a. Disposed thereon are texturing trenches which are formed for optimizing the floating and frictional properties of the magnetic head.
In order to keep pace with the vast improvements in data processing capabilities of conventional computers, hard disk drives with larger capacity and higher storage density are being constantly developed. Recently, a storage density of 200 Mbit/in has been reported. However, significant problems plague such conventional high storage density devices.
The prominence of the extant difficulty among conventional high density storage device is the defects on the recording surface. Indeed, defects measuring less than 1 .mu.m on the recording surface cause substantial errors in writing-in and reading-out of data.
To avoid such defects, the prior art proposes a texturing process which includes polishing with an abrasive tape, containing coarse grained alumina, followed by polishing with a small grained alumina slurry, containing grains measuring less than 2 .mu.m in size. However, this texturing process, results in the formation of relatively deep trenches in the circumferential direction of the disk.
Visual scars and scratches, caused by this texturing process, can be reduced by selecting a suitable abrasive exhibiting abrasive grain dispersivity. Scars can also be reduced by minimizing contact with dust.
However, significant issues remain unaddressed among prior art texturing processes. A major disadvantage of the texturing process described above is that it does not address the micro-scratches which are formed and which can cause substantial errors in writing-in and reading-out of data on the recording media with high storage density.
When the texturing process is performed with the abrasive tapes of alumina grains, a significant number of abrasive grains protruding from the tape surface remain on the base plate. These remaining abrasive grains tend to form deep scars on the base plate. The protruding abrasive grains are primarily caused by coagulation of the alumina grains. Even though the upper parts (peak side) of the deep texturing trenches can be flattened by the subsequent polishing step, the lower parts (valley side) of the deep texturing trenches remain as micro-scratches.
Longstanding problems remain to be solved by the subject matter of the present invention.